Rainsford had dug himself in when he was in France when a seconds delay meant death.
Explanation:
In this line, the author hints at Rainsford's past as a former war hero. We learn that Rainsford was fighting in France during the World War. We also learn that he "dug himself" during his time there. This is most likely a reference to the trenches that were common during WWI, and which became one of the most recognizable images of the war.
